Harq Handling at Inter-Beam Handover

1. A method of operating a controller for a satellite communications system, the method comprising: performing an inter-beam handover by switching communications with a user terminal from a first beam to a second beam of a satellite; receiving a feedback message from the user terminal, via the first beam, after the inter-beam handover is completed; and selectively retransmitting data to the user terminal via the second beam based at least in part on the feedback message received on the first beam after the inter-beam handover.

2. The method of claim 1 , wherein the feedback message includes a negative acknowledgement (NACK) of a forward-link communication sent to the user terminal, via the first beam, prior to the inter-beam handover.

3. The method of claim 2 , wherein the selectively retransmitting comprises: retransmitting, via the second beam, at least a portion of the forward-link communication associated with the feedback message.

4. The method of claim 1 , further comprising: suspending forward-link transmissions to the user terminal on the first beam at least a threshold duration prior to the inter-beam handover.

5. The method of claim 4 , wherein the threshold duration includes at least a processing time for the user terminal to process a forward-link communication.

6. The method of claim 1 , further comprising: receiving a reverse-link communication from the user terminal via the first beam; generating a reverse-link grant message based on the reverse-link communication; and transmitting the reverse-link grant message to the user terminal via the second beam after the inter-beam handover is completed.

7. The method of claim 6 , wherein the reverse-link grant message includes a retransmission request for the reverse-link communication.

8. The method of claim 7 , further comprising: receiving a retransmission of the reverse-link communication via the second beam in response to the reverse-link grant message.

9. The method of claim 8 , wherein the retransmitted communication is received as a new transmission.

10. The method of claim 1 , further comprising: making available to a scheduler for the second beam, upon completing the inter-beam handover, data or information pertaining to one or more ongoing hybrid automatic repeat request (HARQ) processes from the first beam to enable data combining.

11. A controller for a satellite communications system, the controller comprising: one or more processors; and a memory configured to store instructions that, when executed by the one or more processors, cause the controller to: perform an inter-beam handover by switching communications with a user terminal from a first beam to a second beam of a satellite; receive a feedback message from the user terminal, via the first beam, after the inter-beam handover is completed; and selectively retransmit data to the user terminal via the second beam based at least in part on the feedback message received on the first beam after the inter-beam handover.

12. The controller of claim 11 , wherein the feedback message includes a negative acknowledgement (NACK) of a forward-link communication sent to the user terminal, via the first beam, prior to the inter-beam handover.

13. The controller of claim 12 , wherein execution of the instructions to selectively retransmit the data to the user terminal causes the controller to: retransmit, via the second beam, at least a portion of the forward-link communication associated with the feedback message.

14. The controller of claim 11 , wherein execution of the instructions by the one or more processors further causes the controller to: suspend forward-link transmissions to the user terminal on the first beam at least a threshold duration prior to the inter-beam handover.

15. The controller of claim 11 , wherein execution of the instructions by the one or more processors further causes the controller to: receive a reverse-link communication from the user terminal via the first beam; generate a reverse-link grant message based on the reverse-link communication; and transmit the reverse-link grant message to the user terminal via the second beam after the inter-beam handover is completed.

16. The controller of claim 15 , wherein the reverse-link grant message includes a retransmission request for the reverse-link communication.

17. The controller of claim 16 , wherein execution of the instructions by the one or more processors further causes the controller to: receive a retransmission of the reverse-link communication via the second beam in response to the reverse-link grant message, wherein the retransmitted communication is received as a new transmission.

18. The controller of claim 11 , wherein execution of the instructions further causes the controller to: make available to a scheduler for the second beam, upon completing the inter-beam handover, data or information pertaining to one or more ongoing hybrid automatic repeat request (HARQ) processes from the first beam to enable data combining.

19. A controller for a satellite communications system, the controller comprising: means for performing an inter-beam handover by switching communications with a user terminal from a first beam to a second beam of a satellite; means for receiving a feedback message from the user terminal, via the first beam, after the inter-beam handover is completed; and means for selectively retransmitting data to the user terminal via the second beam based at least in part on the feedback message received on the first beam after the inter-beam handover.

20. The controller of claim 19 , wherein the feedback message includes a negative acknowledgement (NACK) of a forward-link communication sent to the user terminal, via the first beam, prior to the inter-beam handover.

21. The controller of claim 20 , wherein the means for selectively retransmitting data to the user terminal is to: retransmit, via the second beam, at least a portion of the forward-link communication associated with the feedback message.

22. The controller of claim 19 , further comprising: means for suspending forward-link transmissions to the user terminal on the first beam at least a threshold duration prior to the inter-beam handover, wherein the threshold duration includes at least a processing time for the user terminal to process a forward-link communication.

23. The controller of claim 19 , further comprising: means for receiving a reverse-link communication from the user terminal via the first beam; means for generating a reverse-link grant message based on the reverse-link communication; and means for transmitting the reverse-link grant message to the user terminal via the second beam after the inter-beam handover is completed.

24. The controller of claim 23 , wherein the reverse-link grant message includes a retransmission request for the reverse-link communication.

25. The controller of claim 24 , further comprising: means for receiving a retransmission of the reverse-link communication via the second beam in response to the reverse-link grant message, wherein the retransmitted communication is received as a new transmission.

26. The controller of claim 19 , further comprising: means for making available to a scheduler for the second beam, upon completing the inter-beam handover, data or information pertaining to one or more ongoing hybrid automatic repeat request (HARQ) processes from the first beam to enable data combining.

27. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a controller for a satellite communications system, cause the controller to perform operations comprising: performing an inter-beam handover by switching communications with a user terminal from a first beam to a second beam of a satellite; receiving a feedback message from the user terminal, via the first beam, after the inter-beam handover is completed; and selectively retransmitting data to the user terminal via the second beam based at least in part on the feedback message received on the first beam after the inter-beam handover.

28. The non-transitory computer-readable medium of claim 27 , wherein the feedback message includes a negative acknowledgement (NACK) of a forward-link communication sent to the user terminal, via the first beam, prior to the inter-beam handover, and wherein execution of the instructions for selectively retransmitting the data to the user terminal causes the controller to perform operations comprising: retransmitting, via the second beam, at least a portion of the forward-link communication associated with the feedback message.

29. The non-transitory computer-readable medium of claim 27 , wherein execution of the instructions by the one or more processors causes the controller to perform operations further comprising: suspending forward-link transmissions to the user terminal on the first beam at least a threshold duration prior to the inter-beam handover, wherein the threshold duration includes at least a processing time for the user terminal to process a forward-link communication.

30. The non-transitory computer-readable medium of claim 27 , wherein execution of the instructions by the one or more processors causes the controller to perform operations further comprising: receiving a reverse-link communication from the user terminal via the first beam; generating a reverse-link grant message based on the reverse-link communication; and transmitting the reverse-link grant message to the user terminal via the second beam after the inter-beam handover is completed.

31. The non-transitory computer-readable medium of claim 30 , wherein the reverse-link grant message includes a retransmission request for the reverse-link communication, and wherein execution of the instructions by the one or more processors causes the controller to perform operations further comprising: receiving a retransmission of the reverse-link communication via the second beam in response to the reverse-link grant message, wherein the retransmitted communication is received as a new transmission.

32. The non-transitory computer-readable medium of claim 27 , wherein execution of the instructions further causes the controller to perform operations comprising: making available to a scheduler for the second beam, upon completing the inter-beam handover, data or information pertaining to one or more ongoing hybrid automatic repeat request (HARQ) processes from the first beam to enable data combining.

33. A method of operating a user terminal in a satellite communications system, the method comprising: transmitting a feedback message to a controller of the satellite communications system, via a first beam of a satellite, to request retransmission of a first set of data previously received by the user terminal; performing an inter-beam handover by switching communications with the controller from the first beam to a second beam of the satellite; and receiving a retransmission of the first set of data via the second beam based at least in part on the feedback message transmitted on the first beam prior to the inter-beam handover.

34. The method of claim 33 , further comprising: combining at least portions of the retransmitted first set of data with the previously received first set of data.

35. The method of claim 33 , further comprising: preserving, during the inter-beam handover, data and information pertaining to one or more hybrid automatic repeat request (HARQ) processes performed via the first beam prior to the inter-beam handover.

36. The method of claim 33 , further comprising: receiving a reverse-link grant message from the controller, via the second beam, after the inter-beam handover is completed; identifying a retransmission request in the reverse-link grant message for a second set of data sent to the controller prior to the inter-beam handover; and retransmitting the second set of data to the controller in response to the retransmission request.

37. The method of claim 36 , wherein the retransmitted second set of data is sent as a new data transmission.

38. A user terminal, comprising: one or more processors; and a memory configured to store instructions that, when executed by the one or more processors, cause the user terminal to: transmit a feedback message to a controller of a satellite communications system, via a first beam of a satellite, to request retransmission of a first set of data previously received by the user terminal; perform an inter-beam handover by switching communications with the controller from the first beam to a second beam of the satellite; and receive a retransmission of the first set of data via the second beam based at least in part on the feedback message transmitted on the first beam prior to the inter-beam handover.

39. The user terminal of claim 38 , wherein execution of the instructions by the one or more processors further causes the user terminal to: combine at least portions of the retransmitted first set of data with the previously received first set of data.

40. The user terminal of claim 38 , wherein execution of the instructions by the one or more processors further causes the user terminal to: preserve, during the inter-beam handover, data and information pertaining to one or more hybrid automatic repeat request (HARQ) processes performed via the first beam prior to the inter-beam handover.

41. The user terminal of claim 38 , wherein execution of the instructions by the one or more processors further causes the user terminal to: receive a reverse-link grant message from the controller, via the second beam, after the inter-beam handover is completed; identify a retransmission request in the reverse-link grant message for a second set of data sent to the controller prior to the inter-beam handover; and retransmit the second set of data to the controller in response to the retransmission request.

42. The user terminal of claim 41 , wherein the retransmitted second set of data is sent as a new data transmission.

43. A user terminal, comprising: means for transmitting a feedback message to a controller of a satellite communications system, via a first beam of a satellite, to request retransmission of a first set of data previously received by the user terminal; means for performing an inter-beam handover by switching communications with the controller from the first beam to a second beam of the satellite; and means for receiving a retransmission of the first set of data via the second beam based at least in part on the feedback message transmitted on the first beam prior to the inter-beam handover.

44. The user terminal of claim 43 , further comprising: means for combining at least portions of the retransmitted first set of data with the previously received first set of data.

45. The user terminal of claim 43 , further comprising: means for preserving, during the inter-beam handover, data and information pertaining to one or more hybrid automatic repeat request (HARQ) processes performed via the first beam prior to the inter-beam handover.

46. The user terminal of claim 43 , further comprising: means for receiving a reverse-link grant message from the controller, via the second beam, after the inter-beam handover is completed; means for identifying a retransmission request in the reverse-link grant message for a second set of data sent to the controller prior to the inter-beam handover; and means for retransmitting the second set of data to the controller in response to the retransmission request, wherein the retransmitted second set of data is sent as a new data transmission.

47. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a user terminal, cause the user terminal to perform operations comprising: transmitting a feedback message to a controller of a satellite communications system, via a first beam of a satellite, to request retransmission of a first set of data previously received by the user terminal; performing an inter-beam handover by switching communications with the controller from the first beam to a second beam of the satellite; and receiving a retransmission of the first set of data via the second beam based at least in part on the feedback message transmitted on the first beam prior to the inter-beam handover.

48. The non-transitory computer-readable medium of claim 47 , wherein execution of the instructions by the one or more processors causes the user terminal to perform operations further comprising: combining at least portions of the retransmitted first set of data with the previously received first set of data.

49. The non-transitory computer-readable medium of claim 47 , wherein execution of the instructions by the one or more processors causes the user terminal to perform operations further comprising: preserving, during the inter-beam handover, data and information pertaining to one or more hybrid automatic repeat request (HARQ) processes performed via the first beam prior to the inter-beam handover.

50. The non-transitory computer-readable medium of claim 48 , wherein execution of the instructions by the one or more processors causes the user terminal to perform operations further comprising: receiving a reverse-link grant message from the controller, via the second beam, after the inter-beam handover is completed; identifying a retransmission request in the reverse-link grant message for a second set of data sent to the controller prior to the inter-beam handover; and retransmitting the second set of data to the controller in response to the retransmission request, wherein the retransmitted second set of data is sent as a new data transmission.